In order to generate visual perception, the light reflected from an object to be perceived must be transmitted through the eye's cornea and focused onto the retina by the crystalline lens of the eye. The aging process or disease states tend to result in diminished functionality or transparency of the crystalline lens, which further leads to deteriorated vision. The degraded visual perception owing to lens damage can be restored through replacing the faulty crystalline lens with a human made artificial lens, or a so-called intraocular lens (IOL). The faulty crystalline generally has to be removed via a surgical procedure, which involves creating a small incision in the anterior capsule where the crystalline lens is located; liquefying the crystalline lens; extracting the liquefied lens; and inserting the IOL into the capsule for replacement using an IOL injecting device.
To squeeze through the small incision made in the cornea, the injection requires the IOL to be temporarily folded or deformed, and the IOL only resumes its original configuration once deposited into the eye successfully. It is possible to create an incision of larger size to facilitate the injection process, but an incision of greater size commonly results in a prolonged healing period and induced astigmatism. Consequently, effort has been put into developing IOLs and the injection devices intended for IOL delivery through incisions sized 3 mm and below. In the past, most of the problems associated with lens insertion have been addressed primarily by improvements in lens design, and to a lesser extent better machined lens cartridges and more sophisticated lens injectors. Particularly, the IOLs with greater resistance against scratching or tearing during the injection process are fabricated from a wide variety of materials like hydrogel, silicon hydrogels, hard polymethyl methacrylate, acrylic resin, and 2-hydroxyethyl methacrylate. Further, improvement is made in IOL configuration. For example, IOLs with plate-shaped haptics have been produced. However, some problems still exist in both the loading step and the actual IOL insertion.
In general, IOL injection devices are designed to be operated single- or two-handed. Most present day commercially available injectors require a two handed approach using a pepper mill action. For instance, Zaleski in U.S. Pat. No. 5,643,276 discloses an injection device furnished with a rotational assembly that can be dialed distally to controllably rotate a rod delivering the lens through an insertion tube inserted into the incision. Another U.S. Pat. No. 7,892,282 provides another rotatably operable lens delivering device by which constant rotation of a drive mechanism on the device causes discrete forward or backward movement of the rod engaging the lens. On the other hand, various single handed devices have been attempted, most resembles a hypodermic syringe. These devices have a tubular body incorporated with a telescopically moveable plunger at one end, and another extreme end with a tapered tip to be inserted into the eye. The plunger pushes the lens, formerly stored in the body of the device or a cartridge attached thereto, into the eye through the tapered tip. An explosive delivery, a tendency of the lens to float upwards, the undesired pushing away of the eye, a non-ergonomic fit in the hand, and a requirement for a large manual expulsion force mean that these IOL injection devices have not been adopted widely. Corresponding injection tools have been devised in respect to some of the above mentioned shortcomings Kobayashi et al. describes a single-handedly operable injection device provided with a posture control member to avoid damaging the IOLs caused by expulsion force induced-deflection at the plunger end engaged to the lens. Further, U.S. Pat. Nos. 6,162,229 and 8,535,332, respectively, offer injection tools carrying a uniquely made plunger tip to expel the IOL from the injector body into the eye in a non-destructive and controlled manner. However, handling these enhanced single-handed IOL injection devices in practical use can be difficult despite the solutions offered to protect the IOL during delivery. Particularly, the dimensions of the prolonged lens delivering tubular body and the bifurcated handles of such injection tools substantially mimic an injection syringe rather than being ergonomically designed to serve IOL delivery. There exist significant differences with regards to administration site and the subject matter to be delivered between an injection syringe and an IOL delivering device. For instance, an IOL delivery procedure can require substantial amount of time to be spent in manipulating the configuration and orientation of the deposited lens, in comparison with medicine injection. In view of this, an IOL injection device that is single-handedly operable and which remedies the aforesaid shortcomings is desired.